Master congenital heart diseases for NEET PG 2026: acyanotic vs cyanotic classification, VSD, ASD, PDA, coarctation, TOF, TGA, Eisenmenger syndrome, CXR and ECG findings, and surgical management.
Version 1.0 — Published March 2026
Congenital heart disease contributes 3–5 questions per NEET PG paper. Master these 8 high-yield areas:
Congenital heart disease (CHD) is a structural abnormality of the heart or great vessels present at birth — occurring in 8–10 per 1,000 live births and representing the most common category of birth defects. In NEET PG, CHD questions span pediatrics (clinical presentation, management), medicine (adult survivors with Eisenmenger), surgery (operative approaches), and radiology (CXR patterns). The student who can classify every lesion by hemodynamics (shunt direction, cyanosis, pulmonary blood flow) and recognize the classic imaging patterns will capture marks across multiple subjects.
This guide covers the complete spectrum of CHDs with the hemodynamic explanations, clinical clues, and imaging findings that NBE tests. Pair this with practice on the Pediatrics subject hub and cross-reference high-yield pediatrics topics for additional neonatal and childhood cardiology content.
Congenital heart disease classification divides lesions into acyanotic (no cyanosis at presentation) and cyanotic (cyanosis present) based on the direction and nature of intracardiac shunting — this is the foundational framework for every CHD question.
This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
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Join on Telegram →| Category | Shunt direction | Pulmonary blood flow | Examples |
|---|---|---|---|
| Acyanotic — left-to-right shunt | Left → Right (oxygenated blood recirculates through lungs) | Increased | VSD, ASD, PDA, AVSD |
| Acyanotic — obstructive | No shunt | Normal or reduced | Coarctation of aorta, aortic stenosis, pulmonary stenosis |
| Cyanotic — decreased pulmonary flow | Right → Left | Decreased | TOF, tricuspid atresia, pulmonary atresia, Ebstein anomaly |
| Cyanotic — increased pulmonary flow | Right → Left (with mixing) | Increased | TGA, truncus arteriosus, TAPVR, HLHS |
Key hemodynamic principle: Left-to-right shunts initially cause volume overload of the pulmonary circulation (pulmonary plethora on CXR, heart failure in infants). Over years, the chronic volume overload causes pulmonary vascular remodeling → fixed pulmonary hypertension → Eisenmenger syndrome (shunt reversal).
Ventricular septal defect (VSD) is an abnormal opening in the interventricular septum allowing left-to-right shunting of blood — accounting for 25–30% of all congenital heart defects and being the single most common CHD.
| Type | Location | Frequency | Key feature |
|---|---|---|---|
| Perimembranous | Membranous septum, below aortic valve | 70–80% | Most common type overall |
| Muscular | Muscular septum | 10–15% | Highest rate of spontaneous closure |
| Outlet (supracristal) | Below pulmonary valve | 5–8% | Common in Asian populations, associated with aortic regurgitation |
| Inlet | Adjacent to AV valves | 5% | Part of AVSD (endocardial cushion defect) |
| VSD size | Hemodynamics | Murmur | Symptoms | Management |
|---|---|---|---|---|
| Small (restrictive) | Small shunt, normal PA pressure | Loud pansystolic murmur at LLSB | Asymptomatic | Observation (50–70% close spontaneously by age 2) |
| Moderate | Moderate shunt, mild PA pressure elevation | Loud murmur + apical diastolic rumble (increased mitral flow) | Mild CHF symptoms | Medical management; surgical closure if symptomatic |
| Large (unrestrictive) | Large shunt, PA pressure = systemic | Soft murmur (paradoxically — equal pressures reduce flow gradient) | Failure to thrive, recurrent pneumonia, severe CHF | Surgical closure before 6 months (to prevent Eisenmenger) |
NBE trap: The loudest VSD murmur comes from the SMALLEST VSD (the pressure gradient across a small restrictive defect is high). A large VSD may have a soft murmur because the equalized pressures create minimal gradient. "Quiet VSD" = large VSD = urgently needs surgery.
Associated finding: Maladie de Roger — an isolated, small, perimembranous VSD with a loud pansystolic murmur but no hemodynamic significance.
Atrial septal defect (ASD) is an abnormal opening in the interatrial septum — the second most common CHD, often asymptomatic until adulthood.
| Type | Location | Frequency | ECG | Association |
|---|---|---|---|---|
| Ostium secundum | Fossa ovalis (mid-septum) | 70% | Incomplete RBBB, right axis deviation | Most common type, isolated |
| Ostium primum | Lower septum (above AV valves) | 15–20% | Left axis deviation, incomplete RBBB | Down syndrome, cleft mitral valve, AVSD |
| Sinus venosus | Near SVC or IVC entry | 5–10% | P-wave axis abnormality | Anomalous pulmonary vein drainage (PAPVR) |
| Coronary sinus | Unroofing of coronary sinus | <1% | Variable | Persistent left SVC |
Treatment: Device closure (catheter-based) for secundum ASD with adequate rims. Surgical closure for primum ASD, sinus venosus ASD, and large secundum ASDs without adequate rims.
Patent ductus arteriosus (PDA) is the persistence of the fetal connection between the aorta and pulmonary artery beyond 72 hours of birth — normally closing functionally within 10–15 hours of birth in response to increased oxygen tension and falling prostaglandin levels.
Anatomy: Connects the aortic isthmus (just distal to left subclavian artery) to the left pulmonary artery.
Clinical features:
Management:
NBE trap: Indomethacin closes the PDA (inhibits prostaglandins). Prostaglandin E1 opens/maintains the PDA. Know when each is needed.
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Start Free Practice →Coarctation of the aorta is a discrete narrowing of the aorta, typically at the level of the ligamentum arteriosum (just distal to the left subclavian artery) — presenting as upper limb hypertension with weak or absent femoral pulses.
Two presentations:
| Feature | Infantile (preductal) | Adult (postductal) |
|---|---|---|
| Age | Neonatal period | Older children/adults |
| Location | Proximal to ductus arteriosus | At or distal to ligamentum arteriosum |
| Duct dependency | Yes (PDA provides lower body flow) | No |
| Presentation | Heart failure, shock when PDA closes | Upper limb hypertension, headaches, claudication |
| Association | Turner syndrome, VSD | Bicuspid aortic valve (85%), berry aneurysms |
| CXR | Cardiomegaly | Rib notching (inferior surface, ribs 3–8 from collateral intercostal arteries), "3" sign or reverse "E" sign |
Classic clinical finding: Blood pressure gradient — upper limb BP >20 mmHg higher than lower limb BP. Radiofemoral delay (femoral pulse delayed compared to radial pulse).
Treatment: Balloon angioplasty with stenting (catheter-based) or surgical repair (resection with end-to-end anastomosis).
Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease — comprising four anatomical abnormalities resulting from a single embryological defect: anterocephalad deviation of the outlet (infundibular) septum.
The four features:
Clinical features:
Investigations:
Definitive surgery: Complete intracardiac repair — VSD closure + relief of RVOTO (infundibular resection + transannular patch). Optimal timing: 3–6 months of age.
Transposition of the great arteries (TGA) is the most common cyanotic CHD presenting in the neonatal period — characterized by the aorta arising from the right ventricle and the pulmonary artery from the left ventricle, creating two parallel circuits.
Hemodynamics: Systemic and pulmonary circulations run in parallel rather than in series. Without mixing (through ASD, VSD, or PDA), the condition is incompatible with life.
Clinical features:
Investigations:
Management:
NBE point: The arterial switch must be performed within 2–3 weeks in simple TGA. After this, the left ventricle (pumping against low-pressure pulmonary circulation) loses muscle mass and cannot sustain systemic pressures after the switch.
Truncus arteriosus is a single arterial trunk arising from both ventricles, giving rise to the aorta, pulmonary arteries, and coronary arteries — always associated with a VSD.
TAPVR is a condition where all four pulmonary veins drain into the systemic venous system instead of the left atrium — an ASD is mandatory for survival (the only pathway for oxygenated blood to reach the left side).
Types: Supracardiac (drains to SVC via vertical vein — most common), cardiac (drains to coronary sinus), infracardiac (drains below diaphragm to IVC/portal vein — worst prognosis due to obstruction), mixed.
CXR: "Snowman sign" (figure-of-8) — supracardiac type only. The dilated vertical vein, innominate vein, and SVC form the upper "snowball," and the heart forms the lower.
Treatment: Surgical — redirect pulmonary veins to left atrium + close ASD.
Eisenmenger syndrome is the irreversible reversal of a left-to-right shunt to right-to-left due to fixed pulmonary hypertension — the dreaded long-term complication of any large unrepaired left-to-right shunt (VSD, ASD, PDA, AVSD).
Pathophysiology:
Clinical features:
Key NBE point: Once Eisenmenger syndrome is established, surgical closure of the original defect is CONTRAINDICATED — removing the "pop-off" valve (the shunt) in the face of fixed pulmonary hypertension causes acute right heart failure and death.
Management:
The diagnostic investigation findings per CHD lesion are tested directly — often as a "match the finding to the diagnosis" question.
| CXR finding | Diagnosis | Mechanism |
|---|---|---|
| Boot-shaped heart | Tetralogy of Fallot | RVH (upturned apex) + absent main PA segment |
| Egg-on-a-string | TGA | Narrow mediastinum (parallel great vessels) |
| Snowman sign (figure-of-8) | TAPVR (supracardiac) | Dilated vertical vein + innominate vein + SVC |
| Rib notching | Coarctation of aorta | Collateral intercostal arteries eroding ribs |
| Pulmonary plethora + cardiomegaly | Large VSD, ASD, PDA | Volume overload from left-to-right shunt |
| Oligemic lung fields | TOF, pulmonary atresia | Reduced pulmonary blood flow |
| Box-shaped heart | Ebstein anomaly | Massive right atrial enlargement |
| ECG finding | Diagnosis |
|---|---|
| Right axis deviation + RVH | TOF, ASD (secundum), pulmonary stenosis |
| Left axis deviation | Primum ASD, AVSD, tricuspid atresia |
| Left ventricular hypertrophy | Large VSD (volume overload), coarctation, aortic stenosis |
| Superior QRS axis | AVSD (endocardial cushion defect) |
| Lesion | Palliative procedure | Definitive surgery | Timing |
|---|---|---|---|
| VSD | PA banding (rarely, for multiple muscular VSDs) | Direct VSD closure | 3–6 months if symptomatic |
| ASD | Not needed | Device closure or surgical | 3–5 years (elective) |
| PDA | Not applicable | Device closure or surgical ligation | When diagnosed |
| Coarctation | PGE1 (neonatal) | Resection + end-to-end anastomosis | When diagnosed |
| TOF | BT shunt (if symptomatic neonate) | Complete intracardiac repair | 3–6 months |
| TGA | Rashkind balloon septostomy | Arterial switch (Jatene) | Within 2 weeks |
| TAPVR | PGE1, balloon septostomy | Pulmonary vein redirection + ASD closure | Neonatal (emergency if obstructed) |
| Truncus arteriosus | Not applicable | Rastelli procedure | Neonatal |
Congenital heart disease contributes 3-5 questions per NEET PG paper across pediatrics, medicine, and surgery. The most tested topics are TOF (tet spell management), VSD (most common CHD), ASD (ostium secundum type), PDA (continuous machinery murmur), and Eisenmenger syndrome. CXR patterns like boot-shaped heart and egg-on-a-string are classic image-based questions.
Ventricular septal defect (VSD) is the most common congenital heart disease, accounting for 25-30% of all CHDs. The perimembranous (membranous) type is the most common VSD subtype. Small restrictive VSDs often close spontaneously by age 2 years. Large unrestrictive VSDs require surgical closure to prevent Eisenmenger syndrome.
Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease overall. TGA (transposition of great arteries) is the most common cyanotic CHD presenting in the neonatal period (first few days of life). The distinction between 'most common cyanotic CHD' (TOF) and 'most common cyanotic CHD in neonates' (TGA) is a classic exam trap.
Tet spell (hypercyanotic spell) management follows a stepwise approach: knee-chest position (increases SVR, reduces right-to-left shunting), oxygen supplementation, IV morphine (reduces respiratory drive and agitation), IV phenylephrine (increases SVR), IV fluids, IV sodium bicarbonate for acidosis. Propranolol is used for prevention of recurrent spells. Emergency surgery if medical management fails.
Eisenmenger syndrome is the reversal of a left-to-right shunt to right-to-left due to pulmonary hypertension from chronic volume overload. Any large unrepaired left-to-right shunt (VSD, ASD, PDA) can cause Eisenmenger syndrome. Once established, surgical correction is contraindicated (the pulmonary vascular disease is irreversible). Treatment is medical: pulmonary vasodilators (sildenafil, bosentan). Heart-lung transplant is the only definitive option.
Ostium secundum ASD (70% of ASDs) is at the fossa ovalis, causes fixed splitting of S2, and shows incomplete RBBB on ECG. Ostium primum ASD is an endocardial cushion defect associated with Down syndrome, causes left axis deviation on ECG, and often has a cleft mitral valve with MR. Sinus venosus ASD is near the SVC entry and is associated with anomalous right pulmonary vein drainage.
Boot-shaped heart (coeur en sabot) is TOF. Egg-on-a-string appearance is TGA. Snowman sign (figure-of-8) is TAPVR (supracardiac type). Box-shaped heart is Ebstein anomaly. Rib notching is coarctation of aorta (older children). Cardiomegaly with pulmonary plethora suggests large left-to-right shunt (VSD, PDA). Oligemic lung fields suggest reduced pulmonary blood flow (TOF, pulmonary atresia).
Prostaglandin E1 (alprostadil) maintains the patent ductus arteriosus open in duct-dependent lesions. It is life-saving in neonates with duct-dependent pulmonary circulation (TOF, pulmonary atresia, tricuspid atresia) where PDA provides pulmonary blood flow, and duct-dependent systemic circulation (coarctation, interrupted aortic arch, HLHS) where PDA provides systemic blood flow.
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This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
Written by: NEETPGAI Editorial Team Reviewed by: Pending SME Review Last reviewed: March 2026
This article is reviewed by qualified medical professionals for clinical accuracy and exam relevance. For corrections or updates, contact the editorial team.